Kadcyla Approved for HER2-Positive Metastatic Breast Cancer

The U.S. Food and Drug Administration (FDA) has approved Kadcyla™ (ado-trastuzumab emtansine, formerly known as T-DM1) for the treatment of HER2-positive, metastatic breast cancer that has been previously treated with Herceptin® (trastuzumab) and taxanes, a class of chemotherapy drugs commonly used to treat breast cancer.

HER2 is a protein involved in normal cell growth. Approximately 20-25% of breast cancers overexpress (make too much of) the HER2 protein, and this over-expression contributes to cancer cell growth and survival. HER2-targeted therapies such as Herceptin have dramatically improved outcomes for women with HER2-positive breast cancer, but researchers continue to explore new approaches to treatment.

Kadcyla combines Herceptin and a chemotherapy drug (DM1) that interferes with cancer cell growth. Kadcyla delivers Herceptin and DM1 directly to HER2-positive cells, and limits exposure of the rest of the body to the chemotherapy.

The approval of Kadcyla was based on a clinical study that included 991 patients who were randomly assigned to receive Kadcyla or Tykerb® (lapatinib) plus Xeloda® (capecitabine). Patients received treatment until cancer progressed or side effects became intolerable. The study was designed to measure progression-free survival and overall survival.

Results indicated that patients treated with Kadcyla had a median progression-free survival of 9.6 months compared to 6.4 months in patients treated with Tykerb/Xeloda. The median overall survival was 30.9 months in the Kadcyla group and 25.1 months in the Tykerb/Xeloda group.

The most common side effects reported in patients treated with Kadcyla were nausea, fatigue, pain in the muscles or joints, low levels of platelets in the blood (thrombocytopenia), increased levels of liver enzymes, headache, and constipation.

Kadcyla was approved under the FDA’s Priority Review Program, which allows an expedited six-month review of drugs that may offer major advances in treatment. Kadcyla will carry a Boxed Warning alerting patients and healthcare professionals that the drug can cause liver toxicity, heart toxicity, and death. The drug can also cause severe life-threatening birth defects, so pregnancy status should be verified prior to intiating Kadcyla treatment.